DESCRIPTION: The investigators have recently developed and described a clinical assay based on reverse transcriptase-chain polymerase assay technology (RT-PCR assay for PSA) that allows them to detect minute amounts of prostate cells present in the circulating blood of prostate cancer patients. In preliminary studies, this test identifies 89% of patients with frank metastatic prostate cancer lesions, as well as a limited subset of patients with suspected clinically localized disease that are candidates for prostate surgery. In order to effectively evaluate the clinical meaning and usefulness of the RT-PCR assay for PSA and to develop more useful permutations of this assay, the following goals are proposed: 1) examine the potential for other prostate cell markers (PSMA and Cytokeratin 18) to confirm the RT-PCR assay for PSA in demonstrating the presence of prostate cancer cells in the blood; 2) determine whether the results of the RT-PCR assay for PSA correlates with the clinical outcome of patients with localized prostate cancer or with metastatic cancer; and 3) to develop a semi-quantitative version of this test that might be of use in identifying the most aggressive forms of prostate cancer. Completion of this project will develop a new and valuable clinical test for the armamentarium against prostate cancer and potentially aid in the understanding of why prostate cancer is more debilitating to minority populations in the United States.